Journal American Society of Mining and Reclamation, 2009
The ultimate goal of mineland reclamation is reestablishment of a productive, functional, and sus... more The ultimate goal of mineland reclamation is reestablishment of a productive, functional, and sustainable ecosystem suitable for postmining land use. Evaluation of reclamation success for bond release, however, is limited to examination of the reestablished plant community with emphasis also placed on soil erosion protection and landscape hydrologic function. Most ecosystem components and processes of the reclaimed site are not examined but are crucial to ecosystem function and sustainability. The objective of this paper is to present data from our work on recovery of ecosystem structure (e.g. organisms, soils, mycorrhiza) and function (e.g. biomass production, carbon cycling, nitrogen cycling) on reclaimed surface coal mines in Wyoming. Our studies of chronosequences of reclaimed sites indicate increasing productivity through time in all groups of organisms monitored (plants, bacteria, fungi, nematodes and arthropods) as well as increasing concentrations of soil organic matter, rapid incorporation of organic carbon into soil aggregates, redevelopment of mycorrhizae, and reformation of carbon and nitrogen pools. Although the precise trajectory of the restored ecosystems are very difficult to predict because of changing control variables such as potential biota (invasive species) and climate, our data indicates ecosystem structure and function is recovering on reclaimed surface minelands.
Journal American Society of Mining and Reclamation, 2009
Soils play a crucial role in the global carbon cycle; they represent a carbon reservoir larger th... more Soils play a crucial role in the global carbon cycle; they represent a carbon reservoir larger than the atmosphere, they are the site of a number of key carbon transformations (e.g. mineralization and humification), and contain a number of unique carbon pools (e.g. plant litter, humic substances, dissolved organic matter, etc.). Land disturbance associated with surface coal mining results in complete disruption of the soil system, loss of a significant portion of soil carbon content, and disturbance of many of the organisms that play critical roles in the carbon cycle (primary producers and decomposers). One of the challenges of surface mine reclamation is reconstruction of a soil system which functions properly in the impacted ecosystem. The objective of this paper is to report our research findings on the recovery of soil carbon pools in reclaimed surface mined lands. Data from our studies indicate 2 mechanisms are important in the rapid accumulation of C from plant litter into soil: physical protection by soil aggregates and biochemical protection of high lignin content. Examination of chronosequences of reclaimed soils indicates plant litter is rapidly incorporated into soil aggregate structure in most of these soils. Lignin content of reclaimed soils we analyzed were higher than that of nearby undisturbed soils, indicating the recalcitrant nature of soil C in reclaimed soils and/or possibly the slow recovery of lignin degrading organisms, primarily fungi. Assays of potentially mineralizable C indicate concentrations of labile C in reclaimed soils reach amounts similar to those in undisturbed soil within 5 or 6 years after revegetation.
Journal American Society of Mining and Reclamation, 2008
Soil organic matter (OM) is drastically reduced by various processes (erosion, leaching, decompos... more Soil organic matter (OM) is drastically reduced by various processes (erosion, leaching, decomposition, dilution through soil horizon mixing etc.) typically associated with topsoil salvage prior to surface mining activities. Of these processes, loss of physical protection of OM through the breaking up of soil aggregation can result in up to 65% of soil carbon (C) reductions. Objectives of this research were to monitor soil aggregate size distribution and associated C throughout short-term stockpiling and subsequent utilization of topsoil for reclamation. Soil samples were collected from the top 5 cm of a stockpile over a 3 year period (<1, 1.5, 3 yrs) and an adjacent undisturbed, native site. Surface stockpile soils were then tracked to a temporary location following stockpile removal and sampled again. Samples were analyzed for aggregate size distribution, fractions, associated C, and OM turnover with 13 C natural abundance. Macroaggregation increased and microaggregation decreased after 3 yrs of storage, indicating recovery of aggregation in 3 yrs. Following the second removal, macroaggregate proportions decreased and silt and clay fractions were greater than that observed in the native site soils. The second disturbance resulted in greater destruction of aggregate structure than the initial disturbance during topsoil salvage. Carbon increased significantly between <1 and 1.5 yrs in both aggregate size classes. Macro-and microaggregate light fraction (LF) C decreased with storage time as this material was available for utilization by microbes. Aggregate δ 13 C values indicated up to 65% new C associated with aggregate structure. Topsoil storage was beneficial for aggregation and associated C in the surface layers only where plant roots and microbial communities are active; however, the second movement of the topsoil resulted in loss of soil aggregation without impact to soil C.
Journal American Society of Mining and Reclamation, 2007
Nitrogen (N) is usually the nutrient most limiting production in semiarid ecosystems and at very ... more Nitrogen (N) is usually the nutrient most limiting production in semiarid ecosystems and at very low concentrations can seriously impact ecosystem processes. Soil from five mines, incorporating a number of commonly used land reclamation practices (grazing vs. un-grazed; stockpiled vs. direct hauled soil; shrub mosaic vs. grass seed mix; and stubble mulch vs. hay mulch), were sampled and analyzed for soil total N (TN) and microbial biomass N (MBN). All mines were located in semiarid Wyoming in either mixed-grass or sagebrush steppe ecosystems. The various management practices investigated appeared to have little influence on TN. Reclaimed soils averaged 30% less TN than undisturbed native soils, suggesting that N could potentially limit vegetation production. Only two reclaimed sites (grass and shrub) at Mine 1 contained a greater mass of TN than an undisturbed site, and while the reason is unclear, greater precipitation (20% higher relative to the other sites sampled) may be responsible. The microbial communities present in undisturbed soils appear to uptake N more efficiently than microbial communities present in reclaimed soil, relative to total soil N. As N fertilizer is only rarely used in Wyoming surface mines, N can only accumulate in a reclaimed soil via wet or dry deposition or by N-fixation by free-living microorganisms or through symbiotic relationships. However, as legumes are typically only a small component of the vegetation, presumably deposition and/or microbial fixation of N are responsible for the majority of N accumulation in these ecosystems. Despite the low TN in reclaimed soils, high plant production on these reclaimed soils suggests that TN is not limiting production.
Effects of large-scale weed invasion on the nature and magnitude of moisture-pulse-driven soil pr... more Effects of large-scale weed invasion on the nature and magnitude of moisture-pulse-driven soil processes in semiarid ecosystems are not clearly understood. The objective of this study was to monitor carbon dioxide (CO 2) and nitrous oxide (N 2 O) emissions and changes in soil carbon (C) and nitrogen (N) following the application of a water pulse in Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) communities dominated by the exotic annual grass cheatgrass (Bromus tectorum) and by the native perennial grass western wheatgrass (Pascopyrum smithii). Sampling locations were established in shrub interspaces dominated by B. tectorum and P. smithi and beneath shrub canopies adjacent to interspaces dominated by B. tectorum and P. smithi, where no grass was present. Soils were classified as fine-loamy, mixed, Borollic Haplargids. Soil samples (0-10 cm) and air samples were collected at 0, 4, 8, 24, 49, 72, and 216 h following additions of 25.4 mm of water. Soil samples were analyzed for dissolved organic carbon (DOC), microbial biomass carbon (MBC), extractable ammonia (NH 4 +), extractable nitrate (NO 3 À), and dissolved organic nitrogen (DON). Grass species induced differences in soil nitrification, N 2 O and CO 2 emissions, and the quantity and timing of labile C available to microbial populations responding to increased moisture availability. In the first 8-h phase after wetting P. smithii soils had the greatest CO 2 emissions compared to other soils but B. tectorum soils had the greatest N 2 O emissions and the greatest increases in CO 2 emissions relative to before wetting. Microbial biomass C in B. tectorum interspace soils increased rapidly but the response was short-lived despite sufficient water availability. After the first 8 h of soil response to wetting, the observed MBC declines in B. tectorum interspace coincided with disproportional DOC and DON concentration increases. Similar DOC and DON increases were also observed in B. tectorum soils beneath shrub canopy. In contrast, DOC and DON concentrations in P. smithii soils remained unaffected by soil wetting and small MBC increases observed during the first 8-h phase did not decline as rapidly as in B. tectorum interspace soils. In conclusion, summer drying-wetting cycles that occur frequently in areas invaded by B. tectorum can accelerate rates of nitrification and C mineralization, and contribute significantly to trace gas emissions from sagebrush-steppe grasslands. With frequent summer rainfall events, the negative consequences B. tectorum presence in the ecosystem can be significant.
Journal American Society of Mining and Reclamation, 2003
The potential to sequester carbon and increase organic nutrient storage in disturbed soils, such ... more The potential to sequester carbon and increase organic nutrient storage in disturbed soils, such as those reclaimed after surface coal mining, appears to be significant. Quantification of organic carbon accumulation is complicated, however, by the presence of coal and coal dust in these soils. Our preliminary data on organic matter content of reclaimed soils at surface coal mines in Wyoming suggest they are sequestering carbon at a rapid rate. Data from a surface mine reclamation site near Hanna, WY indicate that surface (0-15 cm) soil organic carbon content has increased from a low of 10.9 g C kg-1 soil in 1983 to 18.6 g C kg-1 soil in 1998 and to 20.5 g C kg-1 soil in 2002. Undisturbed soil directly adjacent to the reclaimed site has a mean organic carbon content of 15.1 g kg-1 soil. At a mine near Glenrock, WY, soil organic carbon at a site reclaimed in 1979 increased from an estimated low of 5.8 g C kg-1 soil to a current level of 18.4 g C kg-1 soil. Organic carbon content of undisturbed soils adjacent to the reclaimed area range from 9.9 to 15.7 g C kg-1 soil. In contrast to the elevated organic carbon content, amounts of microbial biomass in reclaimed soils at both mines are lower than in nearby undisturbed soils (ca. 60% or less). We have collected similar data from a number of other surface coal mines in Wyoming. We hypothesize that decomposition rates are slow in reclaimed mine soils due to low microbial activity relative to that in undisturbed soils.
Effects of livestock grazing on rangeland soil organic carbon (SOC) dynamics have been variable a... more Effects of livestock grazing on rangeland soil organic carbon (SOC) dynamics have been variable and inconsistent among the ecosystems studied
Changes in soil microbiotic properties such as microbial biomass and community structure in respo... more Changes in soil microbiotic properties such as microbial biomass and community structure in response to alternative management systems are driven by microbial substrate quality and substrate utilization. We evaluated irrigated crop and forage production in two separate four-year experiments for differences in microbial substrate quality, microbial biomass and community structure, and microbial substrate utilization under conventional, organic, and reduced-tillage management systems. The six different management systems were imposed on fields previously under long-term, intensively tilled maize production. Soils under crop and forage production responded to conversion from monocropping to crop rotation, as well as to the three different management systems, but in different ways. Under crop production, four years of organic management resulted in the highest soil organic C (SOC) and microbial biomass concentrations, while under forage production, reduced-tillage management most effectively increased SOC and microbial biomass. There were significant increases in relative abundance of bacteria, fungi, and protozoa, with two-to 36-fold increases in biomarker phospholipid fatty acids (PLFAs). Under crop production, dissolved organic C (DOC) content was higher under organic management than under reduced-tillage and conventional management. Perennial legume crops and organic soil amendments in the organic crop rotation system apparently favored greater soil microbial substrate availability, as well as more microbial biomass compared with other management systems that had fewer legume crops in rotation and synthetic fertilizer applications. Among the forage production management systems with equivalent crop rotations, reduced-tillage management had higher microbial substrate availability and greater microbial biomass than other management systems. Combined crop rotation, tillage management, soil amendments, and legume crops in rotations considerably influenced soil microbiotic properties. More research will expand our understanding of combined effects of these alternatives on feedbacks between soil microbiotic properties and SOC accrual.
ing the sustainable use of rangelands for livestock production. However, many ecosystem component... more ing the sustainable use of rangelands for livestock production. However, many ecosystem components and Growing interest in the potential for soils to provide a sink for processes like plant community structure, soil properatmospheric C has prompted studies of effects of management on the amount and nature of soil organic C (SOC). In this study, we evaluated ties, and nutrient cycling are also affected by grazing effects of different grazing management regimes (light grazing [LG], management (Schuman et al., 1999). Density and duraheavy grazing [HG], and non-grazed exclosures [EX]) on amount tion of rangeland stocking can affect plant community and composition of SOC at the USDA-ARS High Plains Grasslands composition through displacement of cool-season mixed Research Station (HPGRS), Cheyenne, WY. Soils (0-5 cm) from each grasses by warm-season short grasses in northern mixedtreatment were analyzed for total C and N contents and lignin comgrass prairies (Dormaar and Willms, 1990). position. Soil organic C and N contents were significantly greater in Grazing can also influence the amount and composi-LG (SOC-13.8 Mg ha Ϫ1 ; total N-1.22 Mg ha Ϫ1) than HG (SOCtion of SOM (Dormaar and Willms, 1990; Frank et al., 10.9 Mg ha Ϫ1 ; total N-0.94 Mg ha Ϫ1) or EX (SOC-10.8 Mg ha Ϫ1 ; total 1995) through impacts on litter accumulation and deN -0.94 Mg ha Ϫ1). From CuO oxidation studies, significantly greater composition (Naeth et al., 1991; Shariff et al., 1994). (P Ͻ 0.05) total lignin (Vanillyl [V] ϩ Syringyl [S] ϩ Cinnamyl [C] compounds) contents were noted in EX (21 g kg Ϫ1 SOC) than LG The quantity and chemical composition of SOM is im-(12 g kg Ϫ1 SOC) and HG (15 g kg Ϫ1 SOC) soils. The lignin composition portant to C and N cycling, as N is often the productivity of humic (HA) and fulvic (FA) acids indicated that HA under LG limiting factor in rangeland ecosystems (Power, 1994). contained significantly greater V and S than HG or EX. Fulvic acids The extent to which different grazing practices alter C contained S-depleted lignin compared with HAs and FAs from HG, cycling and the composition of SOC is less understood which contained significantly greater V and C than FAs extracted from
Ergosterol is a sterol common to many fungi and may be useful for estimating fungal biomass in so... more Ergosterol is a sterol common to many fungi and may be useful for estimating fungal biomass in soil. Our objective was to compare three different methods for extracting ergosterol from soil. These included: (i) a published method that involves extraction with methanol, saponification with KOH, and separation with hexane before analysis using high-pressure liquid chromatography (HPLC); (ii) a recently published supercritical fluid extraction (SFE) method; and (iii) a simplified extraction method developed in our laboratory that is similar to method (i) but requires 80 to 90% less reagents. Similar quantities of ergosterol were extracted from both prairie and cropland soil with method (i) and with simplified method (iii). In contrast, the SFE method (ii) did not recover naturally occurring ergosterol from soil. Extraction efficiencies of ergosterol standards added to soil were between 75 and 88% for the three procedures, with coefficients of variation of <15% for all methods. Our simplified method substantially reduced cost, extraction time, and chemical waste per sample. Results of this study indicate that the simplified method was the most efficient technique for extraction of ergosterol from soil.
Although a number of techniques are available for estimating the biomass of filamentous microorga... more Although a number of techniques are available for estimating the biomass of filamentous microorganisms in soil, determination of their activity is much more difficult. We report on preliminary studies evaluating the potential use of the volatile microbial secondary metabolites geosmin and methylisoborneol as indicators of activity of filamentous microorganisms. The purge-and-trap technique for analysis of low concentrations of volatile organic compounds in air and water was tested for extracting the earthy-musty odor compounds geosmin and 2-methylisoborneol from soil. Two variations of this method were tried, one in which soil samples were placed in water for purging and another in which samples were purged with no added water. Volatile organic compounds purged from soil were collected on a porous polymer sorbent, Tenax TA. Naturally occurring geosmin and 2-methylisoborneol and added standards were successfully extracted from soil by both methods. Recovery efficiencies, however, were low. Results indicated that wet purging was the most efficacious extraction method yielding maximum recovery rates of added geosmin and 2-methylisoborneol standards of 15 and 24%, respectively.
In recent decades, there has been growing interest among farming and scientific communities towar... more In recent decades, there has been growing interest among farming and scientific communities toward integrated crop–range–livestock farming because of evidence of increased crop production, soil health, environmental services and resilience to increased climatic variability. This paper reviews studies on existing cropping systems and integrated crop–range–livestock systems across the USA which are relevant in the context of summarizing opportunities and challenges associated with implementing long-term crop–range–livestock systems research in the highly variable environment of the central High Plains. With precipitation ranging from 305 to 484mm and uncertain irrigation water supply, this region is especially vulnerable to changing moisture and temperature patterns. The results of our review indicate that diverse crop rotations, reduced soil disturbance and integrated crop–livestock systems could increase economic returns and agroecosystem resilience. Integrating agricultural system ...
Introduction and subsequent invasion of smooth brome (Bromus inermis Leyss.) into native cool-and... more Introduction and subsequent invasion of smooth brome (Bromus inermis Leyss.) into native cool-and warm-season grassland communities has become problematic where presence of native species is important or mandated. The objectives of this study were to examine the efficacy of burning, grazing, and herbicide to reduce smooth brome production and cover while minimizing coincident detrimental effects on cool-season grasses in a reclaimed surface coal mine site. Concurrently, the project also investigated effects of microbial inoculation on respread topsoil subjected to long-term storage and associated effects on seeded cool-season grasses subjected to brome control treatments. Results indicated that grazing and burning were most effective after 2 years of treatment. Smooth brome biomass was lowest in reburned cells (mean 6 SE, 189 6 77 kg ha À1) followed by regrazed (294 6 129) compared to untreated cells (824 6 42) (P , 0.0001). Native grass production was highest in grazed cells (141 6 67 kg ha À1) followed by burning (104 6 41), herbicide (72 6 30), and untreated (30 6 27). Foliar cover response patterns were similar. Inoculation had little effect on microbial biomass and mycorrhizal infection. Retreated cells did show differences among months (P ¼ 0.013) in 2000, and microbial carbon ranged from 0.076 0.01 mg/g in June to 0.12 6 0.01 in July and 0.12 6 0.01 in August, averaged across treatments. Root infection decreased as soil moisture declined. Results indicate grazing offers the greatest potential for controlling smooth brome without harming native, seeded grasses on reclaimed lands in northern mixedprarie communities, and inoculation was unnecessary for enhancing seeded, cool-season grass growth. Resumen La introducció n y subsecuente invasió n del ''Smooth brome'' (Bromus inermis Leyss.) en la comunidades de pastizal de zacates de estació n fría y caliente ha venido a ser problemá tico donde la presencia de las especies nativas es importante o mandatoria. Los objetivos de este estudio fueron examinar la eficacia de la quema, el apacentamiento y los herbicidas para reducir la producció n y cobertura del ''Smooth brome'' minimizando los efectos perjudiciales colaterales sobre los zacates de estació n fría en un sitio en restauració n de una mina superficial de carbó n. El proyecto también examinó los efectos de la inoculació n microbiana sobre el suelo de la capa superficial esparcido en el sitio después de un largo periodo de almacenamiento y los efectos asociados en zacates de estació n fría sembrados y sujetos a tratamientos de control de ''Smooth brome.'' Los resultados indican que el apacentamiento y la quema fueron má s efectivos después de dos añ os de tratamiento. La menor biomasa de ''Smooth brome'' se obtuvo en las á reas re-quemadas (media 6 EE, 189 6 77 kg ha À1),seguida por las á reas re-apacentadas (294 6 129 kg ha À1) comparados con las á reas sin tratar (824 6 42 kg ha À1)(P , 0.0001). La mayor producció n de biomasa de los zacates nativos se obtuvo en las á reas apacentadas (141 6 67 kg ha À1), seguida por las á reas quemadas, con aplicació n de herbicidas y sin tratar con 104 6 41, 72 6 30 y 30 6 27 kg ha À1 respectivamente. Los patrones de respuesta de la cobertura foliar fueron similares. La inoculació n tuvo poco efecto en la biomasa microbiana y la infecció n de micorrizas. En el 2000, las áreas re-tratatadas mostraron diferencias entre meses (P ¼ 0.013) y el carbó n microbiano, promediado entre tratamientos, varió de 0.07 6 0.01 mg/g en Junio a 0.12 6 0.01 en Julio y 0.12 6 0.01 en Agosto. La infecció n radical disminuyó conforme la humedad del suelo disminuyó. Los resultados indican que el apacentamiento ofrece el mayor potencial para controlar el ''Smooth brome'' sin dañ ar a los zacates nativos sembrados en sitios en restauració n de las comunidades de praderas mixtas del norte y la inoculació n fue innecesaria para mejorar el crecimiento de los zacates de estació n fría sembrados.
Although soil structure largely determines energy flows and the distribution and composition of s... more Although soil structure largely determines energy flows and the distribution and composition of soil microhabitats, little is known about how microbial community composition is influenced by soil structural characteristics and organic matter compartmentalization dynamics. A UV irradiation-based procedure was developed to specifically isolate inner-microaggregate microbial communities, thus providing the means to analyze these communities in relation to their environment. Wholeand inner-microaggregate fractions of undisturbed soil and soils reclaimed after disturbance by surface coal mining were analyzed using 16S rDNA terminal restriction fragment polymorphism (T-RFLP) and sequence analyses to determine salient bacterial community structural characteristics. We hypothesized that innermicroaggregate environments select for definable microbial communities and that, due to their sequestered environment, inner-microaggregate communities would not be significantly impacted by disturbance. However, T-RFLP analysis indicated distinct differences between bacterial populations of inner-microaggregates of undisturbed and reclaimed soils. While both undisturbed and reclaimed inner-microaggregate bacterial communities were found dominated by Actinobacteria, undisturbed soils contained only Actinobacteridae, while in innermicroaggregates of reclaimed soils Rubrobacteridae predominate. Spatial stratification of division-level lineages within microaggregates was also evidenced, with Proteobacteria clones being prevalent in libraries derived from whole microaggregates. The fractionation methods employed in this study therefore represent a valuable tool for defining relationships between biodiversity and soil structure.
Most soil microbial community studies to date have focused on homogenized bulk soil samples. Howe... more Most soil microbial community studies to date have focused on homogenized bulk soil samples. However, it is likely that many important microbial processes occur in spatially segregated microenvironments in the soil leading to a microscale biogeography. This study attempts to localize specific microbial populations to different fractions or compartments within the soil matrix. Microbial populations associated with macroaggregates and inner-versus total-microaggregates of three diverse soils were characterized using culture-independent, molecular methods. Despite their relative paucity in most surveys of soil diversity, representatives of Gemmatimonadetes and Actinobacteria subdivision Rubrobacteridae were found to be highly abundant in inner-microaggregates of most soils analyzed. By contrast, clones affiliated with Acidobacteria were found to be relatively enriched in libraries derived from macroaggregate fractions of nearly all soils, but poorly represented in innermicroaggregate fractions. Based upon analysis of 16S rRNA, active community members within microaggregates of a Georgian Ultisol were comprised largely of Gemmatimonadetes and Rubrobacteridae, while within microaggregates of a Nebraska Mollisol, Rubrobacteridae and Alphaproteobacteria were the predominant active bacterial lineages. This work suggests that microaggregates represent a unique microenvironment that selects for specific microbial lineages across disparate soils.
Research on soil fertility is presented in the context of runoff agriculture, a venerable farming... more Research on soil fertility is presented in the context of runoff agriculture, a venerable farming system that has been used for millennia in arid to semiarid regions, where water is a major limiting resource for crop production. The agroecology of runoff farming was studied with the Zuni to evaluate nutrient and hydrologic processes, management, maize productivity, and soil quality in some of the oldest recognized fields in the United States. This ancient Southwest agriculture has functioned without conventional irrigation or fertilization by tapping into biogeochemical processes in natural watersheds connected to fields. Carefully placed fields are managed on alluvial fans and other valley margin landforms to intercept runoff and associated sediment and organic debris transported from adjoining forested uplands. We report on research to evaluate and link nitrogen and phosphorus, two key nutrients for crop production, in watershed, soil, and crop components of this agroecosystem. Nutrient data have been collected by observational and experimental methods for each component and the transport of nutrients from watershed to field to maize. The condition of Zuni agricultural soils suggests that their knowledge and management of soils contributed to effective conservation. This study and others indicate the need for further long-term monitoring and experimental research on watersheds, runoff processes, field soils, and crops across a range of arid to semiarid ecosystems.
This article was published in an Elsevier journal. The attached copy is furnished to the author f... more This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and education use, including for instruction at the author's institution, sharing with colleagues and providing to institution administration. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or b... more All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Soil Microbial Community Recovery in Reclaimed Soils on a Surface Coal Mine Site Soil Biology & Biochemistry T he ultimate goal of mine land reclamation and revegetation is reestablishment of a productive, healthy, and sustainable ecosystem suitable for postmining land use (Munshower, 1994; Harris et al., 1996). Currently, only aboveground indicators such as soil erosion (Mummey et al., 2002a) and vegetation characteristics such as production, cover, diversity, and shrub density (Wick, 2007) are considered in determining reclamation success. Belowground ecosystem structure and function are generally not included as part of reclamation evaluation. When the Surface Mine Control and Reclamation Act was passed in 1977, analysis of ecosystem processes was relatively uncommon and success standards were limited to basic ecological studies (Weigert, 1988; Golley, 1993). Th ere is an immediate need for the consideration of above-and belowground approaches for evaluating reclamation and ensuring long-term reclaimed ecosystem functioning. Productivity and diversity of the plant community reestablished on a reclaimed surface-mined area will depend to a large degree on a range of soil physical, chemical, and biological variables (National Research Council, 1994). Severe perturbations occurring as a result of surface-mining processes can drastically impact these soil variables (Stahl et al., 2002; Ingram et al., 2005). In semiarid climates, reestablished plant communities on reclaimed surface mine lands are oft en more productive and less diverse than nearby undisturbed plant commu
The ultimate goal of mineland reclamation is reestablishment of a productive, functional, and sus... more The ultimate goal of mineland reclamation is reestablishment of a productive, functional, and sustainable ecosystem suitable for postmining land use. Evaluation of reclamation success for bond release, however, is limited to examination of the reestablished plant community with emphasis also placed on soil erosion protection and landscape hydrologic function. Most ecosystem components and processes of the reclaimed site are not
Journal American Society of Mining and Reclamation, 2009
The ultimate goal of mineland reclamation is reestablishment of a productive, functional, and sus... more The ultimate goal of mineland reclamation is reestablishment of a productive, functional, and sustainable ecosystem suitable for postmining land use. Evaluation of reclamation success for bond release, however, is limited to examination of the reestablished plant community with emphasis also placed on soil erosion protection and landscape hydrologic function. Most ecosystem components and processes of the reclaimed site are not examined but are crucial to ecosystem function and sustainability. The objective of this paper is to present data from our work on recovery of ecosystem structure (e.g. organisms, soils, mycorrhiza) and function (e.g. biomass production, carbon cycling, nitrogen cycling) on reclaimed surface coal mines in Wyoming. Our studies of chronosequences of reclaimed sites indicate increasing productivity through time in all groups of organisms monitored (plants, bacteria, fungi, nematodes and arthropods) as well as increasing concentrations of soil organic matter, rapid incorporation of organic carbon into soil aggregates, redevelopment of mycorrhizae, and reformation of carbon and nitrogen pools. Although the precise trajectory of the restored ecosystems are very difficult to predict because of changing control variables such as potential biota (invasive species) and climate, our data indicates ecosystem structure and function is recovering on reclaimed surface minelands.
Journal American Society of Mining and Reclamation, 2009
Soils play a crucial role in the global carbon cycle; they represent a carbon reservoir larger th... more Soils play a crucial role in the global carbon cycle; they represent a carbon reservoir larger than the atmosphere, they are the site of a number of key carbon transformations (e.g. mineralization and humification), and contain a number of unique carbon pools (e.g. plant litter, humic substances, dissolved organic matter, etc.). Land disturbance associated with surface coal mining results in complete disruption of the soil system, loss of a significant portion of soil carbon content, and disturbance of many of the organisms that play critical roles in the carbon cycle (primary producers and decomposers). One of the challenges of surface mine reclamation is reconstruction of a soil system which functions properly in the impacted ecosystem. The objective of this paper is to report our research findings on the recovery of soil carbon pools in reclaimed surface mined lands. Data from our studies indicate 2 mechanisms are important in the rapid accumulation of C from plant litter into soil: physical protection by soil aggregates and biochemical protection of high lignin content. Examination of chronosequences of reclaimed soils indicates plant litter is rapidly incorporated into soil aggregate structure in most of these soils. Lignin content of reclaimed soils we analyzed were higher than that of nearby undisturbed soils, indicating the recalcitrant nature of soil C in reclaimed soils and/or possibly the slow recovery of lignin degrading organisms, primarily fungi. Assays of potentially mineralizable C indicate concentrations of labile C in reclaimed soils reach amounts similar to those in undisturbed soil within 5 or 6 years after revegetation.
Journal American Society of Mining and Reclamation, 2008
Soil organic matter (OM) is drastically reduced by various processes (erosion, leaching, decompos... more Soil organic matter (OM) is drastically reduced by various processes (erosion, leaching, decomposition, dilution through soil horizon mixing etc.) typically associated with topsoil salvage prior to surface mining activities. Of these processes, loss of physical protection of OM through the breaking up of soil aggregation can result in up to 65% of soil carbon (C) reductions. Objectives of this research were to monitor soil aggregate size distribution and associated C throughout short-term stockpiling and subsequent utilization of topsoil for reclamation. Soil samples were collected from the top 5 cm of a stockpile over a 3 year period (<1, 1.5, 3 yrs) and an adjacent undisturbed, native site. Surface stockpile soils were then tracked to a temporary location following stockpile removal and sampled again. Samples were analyzed for aggregate size distribution, fractions, associated C, and OM turnover with 13 C natural abundance. Macroaggregation increased and microaggregation decreased after 3 yrs of storage, indicating recovery of aggregation in 3 yrs. Following the second removal, macroaggregate proportions decreased and silt and clay fractions were greater than that observed in the native site soils. The second disturbance resulted in greater destruction of aggregate structure than the initial disturbance during topsoil salvage. Carbon increased significantly between <1 and 1.5 yrs in both aggregate size classes. Macro-and microaggregate light fraction (LF) C decreased with storage time as this material was available for utilization by microbes. Aggregate δ 13 C values indicated up to 65% new C associated with aggregate structure. Topsoil storage was beneficial for aggregation and associated C in the surface layers only where plant roots and microbial communities are active; however, the second movement of the topsoil resulted in loss of soil aggregation without impact to soil C.
Journal American Society of Mining and Reclamation, 2007
Nitrogen (N) is usually the nutrient most limiting production in semiarid ecosystems and at very ... more Nitrogen (N) is usually the nutrient most limiting production in semiarid ecosystems and at very low concentrations can seriously impact ecosystem processes. Soil from five mines, incorporating a number of commonly used land reclamation practices (grazing vs. un-grazed; stockpiled vs. direct hauled soil; shrub mosaic vs. grass seed mix; and stubble mulch vs. hay mulch), were sampled and analyzed for soil total N (TN) and microbial biomass N (MBN). All mines were located in semiarid Wyoming in either mixed-grass or sagebrush steppe ecosystems. The various management practices investigated appeared to have little influence on TN. Reclaimed soils averaged 30% less TN than undisturbed native soils, suggesting that N could potentially limit vegetation production. Only two reclaimed sites (grass and shrub) at Mine 1 contained a greater mass of TN than an undisturbed site, and while the reason is unclear, greater precipitation (20% higher relative to the other sites sampled) may be responsible. The microbial communities present in undisturbed soils appear to uptake N more efficiently than microbial communities present in reclaimed soil, relative to total soil N. As N fertilizer is only rarely used in Wyoming surface mines, N can only accumulate in a reclaimed soil via wet or dry deposition or by N-fixation by free-living microorganisms or through symbiotic relationships. However, as legumes are typically only a small component of the vegetation, presumably deposition and/or microbial fixation of N are responsible for the majority of N accumulation in these ecosystems. Despite the low TN in reclaimed soils, high plant production on these reclaimed soils suggests that TN is not limiting production.
Effects of large-scale weed invasion on the nature and magnitude of moisture-pulse-driven soil pr... more Effects of large-scale weed invasion on the nature and magnitude of moisture-pulse-driven soil processes in semiarid ecosystems are not clearly understood. The objective of this study was to monitor carbon dioxide (CO 2) and nitrous oxide (N 2 O) emissions and changes in soil carbon (C) and nitrogen (N) following the application of a water pulse in Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) communities dominated by the exotic annual grass cheatgrass (Bromus tectorum) and by the native perennial grass western wheatgrass (Pascopyrum smithii). Sampling locations were established in shrub interspaces dominated by B. tectorum and P. smithi and beneath shrub canopies adjacent to interspaces dominated by B. tectorum and P. smithi, where no grass was present. Soils were classified as fine-loamy, mixed, Borollic Haplargids. Soil samples (0-10 cm) and air samples were collected at 0, 4, 8, 24, 49, 72, and 216 h following additions of 25.4 mm of water. Soil samples were analyzed for dissolved organic carbon (DOC), microbial biomass carbon (MBC), extractable ammonia (NH 4 +), extractable nitrate (NO 3 À), and dissolved organic nitrogen (DON). Grass species induced differences in soil nitrification, N 2 O and CO 2 emissions, and the quantity and timing of labile C available to microbial populations responding to increased moisture availability. In the first 8-h phase after wetting P. smithii soils had the greatest CO 2 emissions compared to other soils but B. tectorum soils had the greatest N 2 O emissions and the greatest increases in CO 2 emissions relative to before wetting. Microbial biomass C in B. tectorum interspace soils increased rapidly but the response was short-lived despite sufficient water availability. After the first 8 h of soil response to wetting, the observed MBC declines in B. tectorum interspace coincided with disproportional DOC and DON concentration increases. Similar DOC and DON increases were also observed in B. tectorum soils beneath shrub canopy. In contrast, DOC and DON concentrations in P. smithii soils remained unaffected by soil wetting and small MBC increases observed during the first 8-h phase did not decline as rapidly as in B. tectorum interspace soils. In conclusion, summer drying-wetting cycles that occur frequently in areas invaded by B. tectorum can accelerate rates of nitrification and C mineralization, and contribute significantly to trace gas emissions from sagebrush-steppe grasslands. With frequent summer rainfall events, the negative consequences B. tectorum presence in the ecosystem can be significant.
Journal American Society of Mining and Reclamation, 2003
The potential to sequester carbon and increase organic nutrient storage in disturbed soils, such ... more The potential to sequester carbon and increase organic nutrient storage in disturbed soils, such as those reclaimed after surface coal mining, appears to be significant. Quantification of organic carbon accumulation is complicated, however, by the presence of coal and coal dust in these soils. Our preliminary data on organic matter content of reclaimed soils at surface coal mines in Wyoming suggest they are sequestering carbon at a rapid rate. Data from a surface mine reclamation site near Hanna, WY indicate that surface (0-15 cm) soil organic carbon content has increased from a low of 10.9 g C kg-1 soil in 1983 to 18.6 g C kg-1 soil in 1998 and to 20.5 g C kg-1 soil in 2002. Undisturbed soil directly adjacent to the reclaimed site has a mean organic carbon content of 15.1 g kg-1 soil. At a mine near Glenrock, WY, soil organic carbon at a site reclaimed in 1979 increased from an estimated low of 5.8 g C kg-1 soil to a current level of 18.4 g C kg-1 soil. Organic carbon content of undisturbed soils adjacent to the reclaimed area range from 9.9 to 15.7 g C kg-1 soil. In contrast to the elevated organic carbon content, amounts of microbial biomass in reclaimed soils at both mines are lower than in nearby undisturbed soils (ca. 60% or less). We have collected similar data from a number of other surface coal mines in Wyoming. We hypothesize that decomposition rates are slow in reclaimed mine soils due to low microbial activity relative to that in undisturbed soils.
Effects of livestock grazing on rangeland soil organic carbon (SOC) dynamics have been variable a... more Effects of livestock grazing on rangeland soil organic carbon (SOC) dynamics have been variable and inconsistent among the ecosystems studied
Changes in soil microbiotic properties such as microbial biomass and community structure in respo... more Changes in soil microbiotic properties such as microbial biomass and community structure in response to alternative management systems are driven by microbial substrate quality and substrate utilization. We evaluated irrigated crop and forage production in two separate four-year experiments for differences in microbial substrate quality, microbial biomass and community structure, and microbial substrate utilization under conventional, organic, and reduced-tillage management systems. The six different management systems were imposed on fields previously under long-term, intensively tilled maize production. Soils under crop and forage production responded to conversion from monocropping to crop rotation, as well as to the three different management systems, but in different ways. Under crop production, four years of organic management resulted in the highest soil organic C (SOC) and microbial biomass concentrations, while under forage production, reduced-tillage management most effectively increased SOC and microbial biomass. There were significant increases in relative abundance of bacteria, fungi, and protozoa, with two-to 36-fold increases in biomarker phospholipid fatty acids (PLFAs). Under crop production, dissolved organic C (DOC) content was higher under organic management than under reduced-tillage and conventional management. Perennial legume crops and organic soil amendments in the organic crop rotation system apparently favored greater soil microbial substrate availability, as well as more microbial biomass compared with other management systems that had fewer legume crops in rotation and synthetic fertilizer applications. Among the forage production management systems with equivalent crop rotations, reduced-tillage management had higher microbial substrate availability and greater microbial biomass than other management systems. Combined crop rotation, tillage management, soil amendments, and legume crops in rotations considerably influenced soil microbiotic properties. More research will expand our understanding of combined effects of these alternatives on feedbacks between soil microbiotic properties and SOC accrual.
ing the sustainable use of rangelands for livestock production. However, many ecosystem component... more ing the sustainable use of rangelands for livestock production. However, many ecosystem components and Growing interest in the potential for soils to provide a sink for processes like plant community structure, soil properatmospheric C has prompted studies of effects of management on the amount and nature of soil organic C (SOC). In this study, we evaluated ties, and nutrient cycling are also affected by grazing effects of different grazing management regimes (light grazing [LG], management (Schuman et al., 1999). Density and duraheavy grazing [HG], and non-grazed exclosures [EX]) on amount tion of rangeland stocking can affect plant community and composition of SOC at the USDA-ARS High Plains Grasslands composition through displacement of cool-season mixed Research Station (HPGRS), Cheyenne, WY. Soils (0-5 cm) from each grasses by warm-season short grasses in northern mixedtreatment were analyzed for total C and N contents and lignin comgrass prairies (Dormaar and Willms, 1990). position. Soil organic C and N contents were significantly greater in Grazing can also influence the amount and composi-LG (SOC-13.8 Mg ha Ϫ1 ; total N-1.22 Mg ha Ϫ1) than HG (SOCtion of SOM (Dormaar and Willms, 1990; Frank et al., 10.9 Mg ha Ϫ1 ; total N-0.94 Mg ha Ϫ1) or EX (SOC-10.8 Mg ha Ϫ1 ; total 1995) through impacts on litter accumulation and deN -0.94 Mg ha Ϫ1). From CuO oxidation studies, significantly greater composition (Naeth et al., 1991; Shariff et al., 1994). (P Ͻ 0.05) total lignin (Vanillyl [V] ϩ Syringyl [S] ϩ Cinnamyl [C] compounds) contents were noted in EX (21 g kg Ϫ1 SOC) than LG The quantity and chemical composition of SOM is im-(12 g kg Ϫ1 SOC) and HG (15 g kg Ϫ1 SOC) soils. The lignin composition portant to C and N cycling, as N is often the productivity of humic (HA) and fulvic (FA) acids indicated that HA under LG limiting factor in rangeland ecosystems (Power, 1994). contained significantly greater V and S than HG or EX. Fulvic acids The extent to which different grazing practices alter C contained S-depleted lignin compared with HAs and FAs from HG, cycling and the composition of SOC is less understood which contained significantly greater V and C than FAs extracted from
Ergosterol is a sterol common to many fungi and may be useful for estimating fungal biomass in so... more Ergosterol is a sterol common to many fungi and may be useful for estimating fungal biomass in soil. Our objective was to compare three different methods for extracting ergosterol from soil. These included: (i) a published method that involves extraction with methanol, saponification with KOH, and separation with hexane before analysis using high-pressure liquid chromatography (HPLC); (ii) a recently published supercritical fluid extraction (SFE) method; and (iii) a simplified extraction method developed in our laboratory that is similar to method (i) but requires 80 to 90% less reagents. Similar quantities of ergosterol were extracted from both prairie and cropland soil with method (i) and with simplified method (iii). In contrast, the SFE method (ii) did not recover naturally occurring ergosterol from soil. Extraction efficiencies of ergosterol standards added to soil were between 75 and 88% for the three procedures, with coefficients of variation of <15% for all methods. Our simplified method substantially reduced cost, extraction time, and chemical waste per sample. Results of this study indicate that the simplified method was the most efficient technique for extraction of ergosterol from soil.
Although a number of techniques are available for estimating the biomass of filamentous microorga... more Although a number of techniques are available for estimating the biomass of filamentous microorganisms in soil, determination of their activity is much more difficult. We report on preliminary studies evaluating the potential use of the volatile microbial secondary metabolites geosmin and methylisoborneol as indicators of activity of filamentous microorganisms. The purge-and-trap technique for analysis of low concentrations of volatile organic compounds in air and water was tested for extracting the earthy-musty odor compounds geosmin and 2-methylisoborneol from soil. Two variations of this method were tried, one in which soil samples were placed in water for purging and another in which samples were purged with no added water. Volatile organic compounds purged from soil were collected on a porous polymer sorbent, Tenax TA. Naturally occurring geosmin and 2-methylisoborneol and added standards were successfully extracted from soil by both methods. Recovery efficiencies, however, were low. Results indicated that wet purging was the most efficacious extraction method yielding maximum recovery rates of added geosmin and 2-methylisoborneol standards of 15 and 24%, respectively.
In recent decades, there has been growing interest among farming and scientific communities towar... more In recent decades, there has been growing interest among farming and scientific communities toward integrated crop–range–livestock farming because of evidence of increased crop production, soil health, environmental services and resilience to increased climatic variability. This paper reviews studies on existing cropping systems and integrated crop–range–livestock systems across the USA which are relevant in the context of summarizing opportunities and challenges associated with implementing long-term crop–range–livestock systems research in the highly variable environment of the central High Plains. With precipitation ranging from 305 to 484mm and uncertain irrigation water supply, this region is especially vulnerable to changing moisture and temperature patterns. The results of our review indicate that diverse crop rotations, reduced soil disturbance and integrated crop–livestock systems could increase economic returns and agroecosystem resilience. Integrating agricultural system ...
Introduction and subsequent invasion of smooth brome (Bromus inermis Leyss.) into native cool-and... more Introduction and subsequent invasion of smooth brome (Bromus inermis Leyss.) into native cool-and warm-season grassland communities has become problematic where presence of native species is important or mandated. The objectives of this study were to examine the efficacy of burning, grazing, and herbicide to reduce smooth brome production and cover while minimizing coincident detrimental effects on cool-season grasses in a reclaimed surface coal mine site. Concurrently, the project also investigated effects of microbial inoculation on respread topsoil subjected to long-term storage and associated effects on seeded cool-season grasses subjected to brome control treatments. Results indicated that grazing and burning were most effective after 2 years of treatment. Smooth brome biomass was lowest in reburned cells (mean 6 SE, 189 6 77 kg ha À1) followed by regrazed (294 6 129) compared to untreated cells (824 6 42) (P , 0.0001). Native grass production was highest in grazed cells (141 6 67 kg ha À1) followed by burning (104 6 41), herbicide (72 6 30), and untreated (30 6 27). Foliar cover response patterns were similar. Inoculation had little effect on microbial biomass and mycorrhizal infection. Retreated cells did show differences among months (P ¼ 0.013) in 2000, and microbial carbon ranged from 0.076 0.01 mg/g in June to 0.12 6 0.01 in July and 0.12 6 0.01 in August, averaged across treatments. Root infection decreased as soil moisture declined. Results indicate grazing offers the greatest potential for controlling smooth brome without harming native, seeded grasses on reclaimed lands in northern mixedprarie communities, and inoculation was unnecessary for enhancing seeded, cool-season grass growth. Resumen La introducció n y subsecuente invasió n del ''Smooth brome'' (Bromus inermis Leyss.) en la comunidades de pastizal de zacates de estació n fría y caliente ha venido a ser problemá tico donde la presencia de las especies nativas es importante o mandatoria. Los objetivos de este estudio fueron examinar la eficacia de la quema, el apacentamiento y los herbicidas para reducir la producció n y cobertura del ''Smooth brome'' minimizando los efectos perjudiciales colaterales sobre los zacates de estació n fría en un sitio en restauració n de una mina superficial de carbó n. El proyecto también examinó los efectos de la inoculació n microbiana sobre el suelo de la capa superficial esparcido en el sitio después de un largo periodo de almacenamiento y los efectos asociados en zacates de estació n fría sembrados y sujetos a tratamientos de control de ''Smooth brome.'' Los resultados indican que el apacentamiento y la quema fueron má s efectivos después de dos añ os de tratamiento. La menor biomasa de ''Smooth brome'' se obtuvo en las á reas re-quemadas (media 6 EE, 189 6 77 kg ha À1),seguida por las á reas re-apacentadas (294 6 129 kg ha À1) comparados con las á reas sin tratar (824 6 42 kg ha À1)(P , 0.0001). La mayor producció n de biomasa de los zacates nativos se obtuvo en las á reas apacentadas (141 6 67 kg ha À1), seguida por las á reas quemadas, con aplicació n de herbicidas y sin tratar con 104 6 41, 72 6 30 y 30 6 27 kg ha À1 respectivamente. Los patrones de respuesta de la cobertura foliar fueron similares. La inoculació n tuvo poco efecto en la biomasa microbiana y la infecció n de micorrizas. En el 2000, las áreas re-tratatadas mostraron diferencias entre meses (P ¼ 0.013) y el carbó n microbiano, promediado entre tratamientos, varió de 0.07 6 0.01 mg/g en Junio a 0.12 6 0.01 en Julio y 0.12 6 0.01 en Agosto. La infecció n radical disminuyó conforme la humedad del suelo disminuyó. Los resultados indican que el apacentamiento ofrece el mayor potencial para controlar el ''Smooth brome'' sin dañ ar a los zacates nativos sembrados en sitios en restauració n de las comunidades de praderas mixtas del norte y la inoculació n fue innecesaria para mejorar el crecimiento de los zacates de estació n fría sembrados.
Although soil structure largely determines energy flows and the distribution and composition of s... more Although soil structure largely determines energy flows and the distribution and composition of soil microhabitats, little is known about how microbial community composition is influenced by soil structural characteristics and organic matter compartmentalization dynamics. A UV irradiation-based procedure was developed to specifically isolate inner-microaggregate microbial communities, thus providing the means to analyze these communities in relation to their environment. Wholeand inner-microaggregate fractions of undisturbed soil and soils reclaimed after disturbance by surface coal mining were analyzed using 16S rDNA terminal restriction fragment polymorphism (T-RFLP) and sequence analyses to determine salient bacterial community structural characteristics. We hypothesized that innermicroaggregate environments select for definable microbial communities and that, due to their sequestered environment, inner-microaggregate communities would not be significantly impacted by disturbance. However, T-RFLP analysis indicated distinct differences between bacterial populations of inner-microaggregates of undisturbed and reclaimed soils. While both undisturbed and reclaimed inner-microaggregate bacterial communities were found dominated by Actinobacteria, undisturbed soils contained only Actinobacteridae, while in innermicroaggregates of reclaimed soils Rubrobacteridae predominate. Spatial stratification of division-level lineages within microaggregates was also evidenced, with Proteobacteria clones being prevalent in libraries derived from whole microaggregates. The fractionation methods employed in this study therefore represent a valuable tool for defining relationships between biodiversity and soil structure.
Most soil microbial community studies to date have focused on homogenized bulk soil samples. Howe... more Most soil microbial community studies to date have focused on homogenized bulk soil samples. However, it is likely that many important microbial processes occur in spatially segregated microenvironments in the soil leading to a microscale biogeography. This study attempts to localize specific microbial populations to different fractions or compartments within the soil matrix. Microbial populations associated with macroaggregates and inner-versus total-microaggregates of three diverse soils were characterized using culture-independent, molecular methods. Despite their relative paucity in most surveys of soil diversity, representatives of Gemmatimonadetes and Actinobacteria subdivision Rubrobacteridae were found to be highly abundant in inner-microaggregates of most soils analyzed. By contrast, clones affiliated with Acidobacteria were found to be relatively enriched in libraries derived from macroaggregate fractions of nearly all soils, but poorly represented in innermicroaggregate fractions. Based upon analysis of 16S rRNA, active community members within microaggregates of a Georgian Ultisol were comprised largely of Gemmatimonadetes and Rubrobacteridae, while within microaggregates of a Nebraska Mollisol, Rubrobacteridae and Alphaproteobacteria were the predominant active bacterial lineages. This work suggests that microaggregates represent a unique microenvironment that selects for specific microbial lineages across disparate soils.
Research on soil fertility is presented in the context of runoff agriculture, a venerable farming... more Research on soil fertility is presented in the context of runoff agriculture, a venerable farming system that has been used for millennia in arid to semiarid regions, where water is a major limiting resource for crop production. The agroecology of runoff farming was studied with the Zuni to evaluate nutrient and hydrologic processes, management, maize productivity, and soil quality in some of the oldest recognized fields in the United States. This ancient Southwest agriculture has functioned without conventional irrigation or fertilization by tapping into biogeochemical processes in natural watersheds connected to fields. Carefully placed fields are managed on alluvial fans and other valley margin landforms to intercept runoff and associated sediment and organic debris transported from adjoining forested uplands. We report on research to evaluate and link nitrogen and phosphorus, two key nutrients for crop production, in watershed, soil, and crop components of this agroecosystem. Nutrient data have been collected by observational and experimental methods for each component and the transport of nutrients from watershed to field to maize. The condition of Zuni agricultural soils suggests that their knowledge and management of soils contributed to effective conservation. This study and others indicate the need for further long-term monitoring and experimental research on watersheds, runoff processes, field soils, and crops across a range of arid to semiarid ecosystems.
This article was published in an Elsevier journal. The attached copy is furnished to the author f... more This article was published in an Elsevier journal. The attached copy is furnished to the author for non-commercial research and education use, including for instruction at the author's institution, sharing with colleagues and providing to institution administration. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or b... more All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher. Soil Microbial Community Recovery in Reclaimed Soils on a Surface Coal Mine Site Soil Biology & Biochemistry T he ultimate goal of mine land reclamation and revegetation is reestablishment of a productive, healthy, and sustainable ecosystem suitable for postmining land use (Munshower, 1994; Harris et al., 1996). Currently, only aboveground indicators such as soil erosion (Mummey et al., 2002a) and vegetation characteristics such as production, cover, diversity, and shrub density (Wick, 2007) are considered in determining reclamation success. Belowground ecosystem structure and function are generally not included as part of reclamation evaluation. When the Surface Mine Control and Reclamation Act was passed in 1977, analysis of ecosystem processes was relatively uncommon and success standards were limited to basic ecological studies (Weigert, 1988; Golley, 1993). Th ere is an immediate need for the consideration of above-and belowground approaches for evaluating reclamation and ensuring long-term reclaimed ecosystem functioning. Productivity and diversity of the plant community reestablished on a reclaimed surface-mined area will depend to a large degree on a range of soil physical, chemical, and biological variables (National Research Council, 1994). Severe perturbations occurring as a result of surface-mining processes can drastically impact these soil variables (Stahl et al., 2002; Ingram et al., 2005). In semiarid climates, reestablished plant communities on reclaimed surface mine lands are oft en more productive and less diverse than nearby undisturbed plant commu
The ultimate goal of mineland reclamation is reestablishment of a productive, functional, and sus... more The ultimate goal of mineland reclamation is reestablishment of a productive, functional, and sustainable ecosystem suitable for postmining land use. Evaluation of reclamation success for bond release, however, is limited to examination of the reestablished plant community with emphasis also placed on soil erosion protection and landscape hydrologic function. Most ecosystem components and processes of the reclaimed site are not
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